Rasearch On Routing And Resource Management Technology For Space Optical Network

The booming evolution of big data and mobile Internet services is calling for the promotion of the transmission capacity and transmission rate of satellite communication systems.Optical satellite network offers many potential advantages of very wide bandwidth,unlicensed spectrum,security,and resistance to jamming,making space laser communication a hot topic in the current communication field.Recently,space laser communication has evolved from point-to-point communication to global coverage and real-time communication network.Therefore,the use of laser communication technology to establish inter-satellite links to form satellite high-speed optical Internet is the development trend of large-capacity and high-rate communications in future space information networks.However,the space optical network is still facing the following challenges:Doppler wavelength shift caused by the relative motion of satellites can adversely affect the quality of communications;the high dynamics of satellite networks and the uneven distribution of global traffic intensity can easily lead to the unbalanced distribution of the entire network load;the contradiction between higher and higher user demands and scarce bandwidth resources has become increasingly prominent.The research on the routing and resource management technology of the space optical network is carried out for the sake of solving the above problems,improving the network robustness and guaranteeing the quality of service(QoS)of the users.In view of the requirements for inter-satellite optical transmission path establishment,effective multi-user access as well as system simulation and verification support,this paper focuses on the routing and wavelength allocation technologies,resource management technologies,and high-level architecture(HLA)simulation technologies involved in space optical networks.The above studies aim to achieve reliable communications between any two users at any time and any place.The main research contents and innovations of this paper are as follows:(1)Ant Colony Routing and Wavelength Assignment Algorithm Based on Cross-Layer DesignTo overcome the adverse effects of Doppler wavelength shift on data transmission in space optical networks,an ant colony routing and wavelength assignment algorithm based on cross-layer design(CL-ACRWA)is proposed.A cross-layer optimization model is built,which makes the routing algorithm of the network layer apply Doppler wavelength shift,transmission delay as well as wavelength usage information of the physical layer.Then an ant colony algorithm is utilized to solve the cross-layer optimization model.And the positive and negative feedback mechanism is adopted to update pheromones,making the ants effectively avoid the optical inter-satellite links(ISL)whose Doppler wavelength shift is greater than the threshold when searching for the optimal lightpath.The performance of the proposed algorithm is simulated and verified in two kinds of space optical networks:Iridium and Next-generation Low-earth-orbit System(NeLS).The results show that compared with ant colony optimization with small window strategy algorithm(ACO-SWS)and original ant colony optimization algorithm(ACO-Original),CL-ACRWA greatly improves the communication success probability while ensuring better global search ability and fast convergence speed.Meanwhile,the transmission delay can meet the basic requirement of real-time transmission of business.(2)Ant Colony Optimization Based Load Balancing Routing and Wavelength Assignment AlgorithmFor the sake of achieving a fairy load balancing over the entire space optical networks,an ant colony optimization based load balancing routing and wavelength assignment algorithm(ALRWA)was put forward.ALRWA establishes an ant colony optimization model from the two dimensions of global traffic distribution and local ISL load status.This model not only uses the relative traffic intensity of satellite coverage area to modify the cost of optical ISLs,but also applies the auto regressive moving average mixed model to observe the wavelength utilization of optical ISLs,making the lightpath tend to select satellites covering non-hot spot areas and avoid the optical ISL with high load for a long time effectively.The performance of the proposed algorithm is simulated and verified in two kinds of space optical networks:Iridium and NeLS.Simulation results show that compared with ACO-SWS and ACO-Original,ALRWA performs well in blocking probability and realizes efficient load balancing.Meanwhile,the average transmission delay can meet the basic requirement of real-time business transmission.(3)Unified Utility Function Based Cross-Layer Design of Dynamic Bandwidth Allocation AlgorithmIn order to solve the contradiction between the increasing user demand and the scarce bandwidth resources,a cross-layer design of dynamic bandwidth allocation for space optical networks based on unified utility function(UUF-CL-DBA)is proposed.A network utility optimization model is designed firstly.On the one hand,a unified utility function is applied to meet the performance requirements for different services.On the other hand,the cross-layer design concept is introduced,realizing that the dynamic bandwidth allocation(DBA)method in the media access control layer takes into account business priority from the application layer,as well as modulation order and code efficiency from the physical layer.Then,the adaptive genetic algorithm is used to solve the optimization model,leading to allocate reasonable resources for each user.The performance of the proposed algorithm is compared with fair water-based cross-layer DBA algorithm and utility maximization-based cross-layer DBA algorithm.Simulation results show that UUF-CL-DBA performs well in network utility,user satisfaction and system throughput,meanwhile,satisfies the absolute fairness of the users.(4)High Level Architecture Based Research on Hardware in Loop Simulation Mechanism of Broadband Satellite Communication SystemHLA distributed simulation technology has the ability to build a large-scale simulation platform,which can guarantee the reusability of simulation resources and the modeling and interoperability between simulation applications.In order to simulate and display space optical networks from the aspects of dynamic composition of the network,real-time monitoring of system performance,and the loading of actual user service,a HLA-based hardware in loop simulation platform of broadband satellite communication system is conducted.On the basis of the study of HLA protocol,the interconnection and interoperation between the OPNET application of satellite network simulation,the MATLAB application of system performance analysis,the STK application of network node display and the VC application of real service acquisition are realized.The platform not only more stereoscopically demonstrates that real voice services are transmitted from one client to another via a virtual broadband satellite communication network,but also analyzes the system performance of satellite coverage,end-to-end delay,network throughput and so on.This study provides the foundation for system-level simulation and verification of space optical networks.